Instead of becoming infirm and dying early as untreated mice did, animals that got the stem/progenitor cells improved their health and lived two to three times longer than expected.

“Our experiments showed that mice that have progeria, a disorder of premature aging, were healthier and lived longer after an injection of stem cells from young, healthy animals,” said Dr. Laura Niedernhofer, associate professor in Pitt’s Department of Microbiology and Molecular Genetics and the University of Pittsburgh Cancer Institute. “That tells us that stem cell dysfunction is a cause of the changes we see with aging.”

Typically the progeria mice die at around 21 to 28 days of age, but the treated animals lived far longer — some even lived beyond 66 days. They also were in better general health, the researchers said.

Unknown molecules from stem cells block aging

As the progeria mice age, they lose muscle mass in their hind limbs, hunch over, tremble, and move slowly and awkwardly. Affected mice that got a shot of stem cells just before showing the first signs of aging were more like normal mice, and they grew almost as large. Closer examination showed new blood vessel growth in the brain and muscle, even though the stem/progenitor cells weren’t detected in those tissues.

In fact, the cells didn’t migrate to any particular tissue after injection into the abdomen. “This leads us to think that healthy cells secrete factors to create an environment that help correct the dysfunction present in the native stem cell population and aged tissue,” Dr. Niedernhofer said. “In a culture dish experiment, we put young stem cells close to, but not touching, progeria stem cells, and the unhealthy cells functionally improved.”

The provocative findings urge further research, she added. They hint that it might be possible one day to forestall the biological declines associated with aging by delivering a shot of youthful vigor, particularly if specific rejuvenating proteins or molecules produced by the stem cells could be identified and isolated.